A gun is a mechanical device that fires projectiles at high velocity, using a propellant such as gun powder or compressed air. The projectile, usually designated by its diameter in inches (caliber) or millimeters, is fired through a hollow tube known as the gun's barrel. Related to muskets, the modern gun is more advanced in technology.
The term "gun" is often used as a synonym to firearm, but in military usage the term refers only to artillery that fires projectiles at high velocity, such as anti-aircraft artillery, field guns, tank guns, anti-tank guns and naval guns. A gunner is a member of the team charged with the task of operating and firing a gun. Mortars and all hand-held firearms are excluded from this definition. The exception to this is the shotgun, which is hand-held, has a smooth bore and fires a cartridge of pellets or a single projectile known as a slug.
See the related article on firearms for information on weapons informally known as guns.
3-Gun Tactical - 3-Gun Tactical competition uses three guns: a handgun, shotgun, and a rifle. Any handgun, shotgun, or rifle can be used. Two stages are scored: combined handgun/shotgun and combined handgun/rifle.